New enhanced sensitivity infrared laser spectroscopy techniques applied to reactive plasmas and trace gas detection [Elektronische Ressource] / vorgelegt von Stefan Welzel

New Enhanced Sensitivity Infrared Laser Spectroscopy Techniques Applied to Reactive Plasmas and Trace Gas Detection INAUGURALDISSERTATION zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) an der Mathematisch-Naturwissenschaftlichen Fakultät der Ernst-Moritz-Arndt-Universität Greifswald vorgelegt von Stefan Welzel geboren am 6. Mai 1979 in Meerane Greifswald, 9. Juni 2009 Dekan: Prof. Dr. K. Fesser 1. Gutachter : Prof. Dr. J. Röpcke 2. Gutachter: Prof. Dr. N. Sadeghi Tag der Promotion: 9. Oktober 2009 Abstract 5 Abstract Infrared laser absorption spectroscopy (IRLAS) employing both tuneable diode and quantum cascade lasers (TDLs, QCLs) has been applied with both high sensitivity and high time resolution to plasma diagnostics and trace gas measurements. TDLAS combined with a conventional White type multiple pass cell was used to detect up to 13 constituent molecular species in low pressure Ar/H /N /O and Ar/CH /N /O 2 2 2 4 2 2microwave discharges, among them the main products such as H O, NH , NO and CO, HCN 2 3respectively. The hydroxyl radical has been measured in the mid infrared (MIR) spectral 11 12 -3range in-situ in both plasmas yielding number densities of between 10 ... 10 cm .